This invention relates to a brake-actuating mechanism for use on a drum brake device, designed to mechanically move a pair of brake shoes away from each other in response to operation of an operating lever. More particularly, it relates to a brake cable-connecting apparatus designed to permit a brake cable to remain connected on the operating lever, even during transportation of the drum brake device.
One known type of a prior art brake cable-connecting apparatus of a brake-actuating mechanism as described above is illustrated in FIGS. 14a and 14b, disclosed in Japanese Patent Application Laid-Open No. 2000-108855.
In FIGS. 14a and 14b, a strut, an operating lever and a brake cable are identified by reference numerals 1, 2 and 3, respectively. As described below, these components comprise a drum brake-actuating mechanism in cooperation.
A brake shoe engagement groove 1a is formed at one end of the strut 1, with which one brake shoe (not shown) is engaged. The operating lever 2 is pivotably supported on the strut 1 in a state in which a proximal end of the lever 2 is pivoted about the other end of the strut 1 by means of a pivot pin 4. A brake shoe engagement groove 2a is formed at the proximal end of the operating lever 2, with which the other brake shoe (not shown) is engaged.
As illustrated in FIG. 14b, a cable end engagement recess 2b is formed at a free end of the lever 2, with which a cable end 3a of the brake cable 3 is engaged in a brake cable pulling direction, or rather in a cable operating direction.
In the above structure, when a cable-pulling force indicated by arrow xe2x80x9cWxe2x80x9d is actuated on the operating lever 2 via the brake cable 3, then the operating lever 2 rotates about the pin 4 in a corresponding direction, thereby thrusting the corresponding brake shoe in a leftward direction of FIG. 14b. 
Such rotational movement of the lever 2 imparts a counterforce to the strut 1, thereby pushing the strut 1 together with the corresponding brake shoe in a rightward direction of FIG. 14b. 
The action of the brake shoes away from each other causes the brake shoes to be pressed against an inner circumferential surface of a brake drum (not shown), thereby providing a predetermined braking action.
In order to engage the cable end 3a with the cable end engagement recess 2b at the free end of the lever 2, the brake cable 3 (cable end 3a) is initially inserted into the brake-actuating mechanism as shown by arrows in FIG. 14a, and then the cable end 3a is positioned above the cable end engagement recess 2b. The brake cable 3 is pulled in the operating direction as shown by arrows in FIG. 14b, thereby engaging the cable end 3a with the cable end engagement recess 2b. 
The drum brake device is sometimes transported in a state that the brake cable 3 (the cable end 3a) is installed to the operating lever 2. In this case, easy disengagement of the brake cable 3 (the cable end 3a) from the operating lever 2 significantly reduces operability.
As disclosed in the above-described prior art, conventional practice to prevent such disengagement is that the width of an opening of the cable end engagement recess 2b is made smaller than a diameter of the cable end 3a so that a great pulling force must be actuated on the brake cable 3 at the final step as shown by the arrow in FIG. 14b in order to insert the cable end 3a into the brake cable engagement recess 2b. Such a proposal has been made to provide a countermeasure to avoid disengaging the brake cable 3 (the cable end 3a) from the operating lever 2 during transportation of the drum brake device.
However, such a conventional countermeasure impairs operability because the cable end 3a must be inserted into the brake cable engagement recess 2b with the great force. This means that cable-connecting operability is sacrificed for engagement of the cable end with the brake cable engagement recess 2b, and this is an impractical method.
Since the end 3a is forcedly inserted into the brake cable engagement recess 2b by the great force, the end 3a and the opening of the brake cable engagement recess 2b may be damaged or deformed. This is an impractical method as well.
According to a first aspect of the present invention, an object of the invention is to obviate the above problem by means of another countermeasure that substantially differs in idea from the above-described prior art, and further to provide an improved brake cable-connecting apparatus designed to engage a cable end of the brake cable in positive engagement with a cable end engagement recess of an operating lever at a free end thereof, with little increase in effort required for engaging the cable end with the cable end engagement recess, without a sacrifice of cable-connecting operability, and without damage or deformation of the cable end and the opening of cable end engagement recess.
In order to accomplish this object, in the first aspect, a brake cable-connecting apparatus of a brake-actuating mechanism for use on a drum brake, the brake actuating mechanism comprises: a strut engaging with one of a pair of brake shoes at one end thereof; an operating lever, being pivotably attached to the strut at the other end of the strut, engaging with the other of the brake shoes at the other end thereof; a brake cable, a cable end thereof engaging with a free end of the operating lever in a cable operating direction so as to rotate the operating lever relative to the strut with a pivotal attachment portion by applying a brake cable-pulling force on the free end of the operating lever, thereby moving the brake shoes in a direction away from each other. Notably, a resilient member is extending into a path in which the cable end moves when the cable end engages with the free end of the operating lever and is positioned to interfere with the cable end so that the cable end can pass over the resilient member with sufficiently resiliently. The resilient member is deformed by the cable end when the cable end moves in the path in the cable operating direction, while the cable end can not pass over the resilient member when the cable end moves in the path in a cable releasing direction substantially opposite to said cable operating direction.
When the brake cable-pulling force is imposed on the free end of the operating lever via the cable end, then the operating lever and strut are relatively pivoted with respect to each other about the pivotal attachment portion, thereby moving the brake shoes away from each other. In engaging the cable end with the fee end of the operating lever, a brake cable is pulled by light force, and the cable end is thereby held against the free end of the operating lever.
According to the first aspect of the invention, the use of the resilient member makes it feasible to engage the cable end in positive engagement with a cable end engagement portion of the operating lever at the free end thereof, with little increase in effort required for holding the cable end in engagement with the free end of the operating lever, without a sacrifice of cable-connecting operability, and without damage or deformation of the cable end and the cable end engagement portion.
According to a second aspect of the present invention, an object of the invention is to provide an improved brake cable-connecting apparatus wherein the operation and effects according to the first aspect of the invention are achievable by means of a low cost countermeasure including a plate spring.
In the second aspect of a brake cable-connecting apparatus as defined in the first aspect of the invention, the resilient member is formed by a plate spring disposed so as to be resiliently deformed in a thickness direction of the plate spring by the cable end when the cable end runs in the path in the operating and releasing directions. For the second aspect, the resilient deformation in the cable operating direction is designed to allow the movement of the cable end through the path in the cable operating direction and to restrict the movement in the cable releasing direction.
Pursuant to the second aspect of the invention, the operation and effects as provided in the first aspect of the invention is achievable by means of a low cost countermeasure including the plate spring.
According to a third aspect of the present invention, an object of the invention is to provide an improved brake cable-connecting apparatus designed to allow the plate spring according to the second aspect of the invention to be simply disposed therein at low cost.
In the third aspect of a brake cable-connecting apparatus as defined in the second aspect of the invention, the plate spring is supportingly mounted on a pivot pin used to pivotably attach the operating lever to the strut at the other end of the strut.
Pursuant to the third aspect of the invention, it is advantageous in that the plate spring according to the second aspect of the invention can simply be disposed in the brake cable-connecting apparatus at low cost.
According to a fourth aspect of the invention, an object of the invention is to provide an improved brake cable-connecting apparatus designed to provide the operation and effects according to the first aspect of the invention at lower cost.
The fourth aspect of the invention provides a brake cable-connecting apparatus as defined in the third aspect of the invention, wherein the strut includes a pair of opposed sidewalls and a bridge portion that spans between the sidewalls. The free end of the operating lever is interposed between the sidewalls at both sides of the operating lever in a pivotal axial direction of the operating lever, and the resilient deformation of the plate spring is defined by the bridge portion and is designed to restrict the movement of the cable end in the path in the cable releasing direction over resilient member.
Pursuant to the fourth aspect of the invention, the operation and effects according to the first aspect of the invention are achievable at lower cost because the starting point of the resilient deformation of the plate spring is defined by one part of the strut when the cable end moves in the path in the cable releasing direction.
According to a fifth aspect of the invention, an object of the invention is to provide an improved brake cable-connecting apparatus designed to provide the operation and effects according to the first aspect of the invention at further lower cost.
In the fifth aspect of a brake cable-connecting apparatus as defined in the third or fourth aspect of the invention, the free end of the operating lever is formed into a forked leg with which at least one end of the cable end engages in the pivotal axial direction of the operating lever, and wherein the starting point of the resilient deformation of the plate spring where the cable end can run in the path in the operating direction over resilient member is decided by a proximal portion of the forked leg.
Pursuant to the fifth aspect of the invention, the operation and effects according to the first aspect of the invention are achievable at further lower cost because the starting point of the resilient deformation of the plate spring is defined by one part of the operating lever when the cable end moves in the path in the cable operating direction.
According to a sixth aspect of the invention, an object of the invention is to provide an improved brake cable-connecting apparatus designed to provide the operation and effects according to the first aspect of the invention by means of a low cost countermeasure including a plate spring that differs from the plate spring according to the second aspect of the invention.
In the sixth aspect of a brake cable-connecting apparatus as defined in the first aspect of the invention, the resilient member is formed by a plate spring disposed to permit the cable end to pass over the resilient member by sufficiently resilient deformation in a thickness direction of the plate spring by the cable end when the cable end moves in the path in the cable operating direction. However, in the sixth aspect, the system is not able to resiliently deform the resilient member due to a force from the cable end in the transverse direction of the plate spring when the cable end moves in the path in the cable releasing direction.
Pursuant to the sixth aspect of the invention, since the plate spring cannot resiliently deform when the cable end moves in the cable releasing direction, a low cost countermeasure formed by the plate spring is able to hold the cable end in engagement with the free end of the operating lever.
When the cable end is moving in the path in the cable operating direction, it is possible that the cable end passes over the plate spring while resiliently deforming the plate spring in the thickness direction of the plate spring, the above-described operation and effects are achievable. For example, it is possible to achieve the disengagement of the cable end from the cable end engagement portion of the operating lever at the free end thereof, with little increase in effort required for engaging the cable end with the free end of the operating lever, without a sacrifice of cable-connecting operability, and without damage or deformation of the cable end and the cable end engagement portion.
According to a seventh aspect of the invention, an object of the invention is to provide an improved brake cable-connecting apparatus designed to reliably provide the operation and effects according to the sixth aspect of the invention by means of a pair of plate springs.
In the seventh aspect of a brake cable-connecting apparatus as defined in the sixth aspect of the invention, a pair of plate springs fixedly attached to the operating lever in such a manner that planar surfaces of the plate springs are positioned parallel to a pivotal surface of the operating lever, respective bent portions being provided at free ends of the plate springs. The bent portions are pushed away from each other by corresponding end surfaces of the cable end in the pivotal axial direction of the operating lever when the cable end moves in the path in the cable operating direction, thereby resiliently deforming the plate springs in the thickness direction of the plate springs, while at least one end of the cable end in the pivotal axial direction of the operating lever abuts against tips of the bent portions so as to cause forces acting in the transverse direction of the plate springs to be actuated on the plate springs when the cable end moves in the path in the cable releasing direction, thereby precluding resilient deformation of the plate springs.
Pursuant to the seventh aspect of the invention, the pair of plate springs holds the cable end in position at both ends of the cable end, and the operation and effects according to the sixth aspect of the invention are reliably provided.
According to an eighth aspect of the invention, an object of the invention is to provide an improved brake cable-connecting apparatus designed for easier installation of the pair of plate springs according to the seventh aspect of the invention.
In the eighth aspect of a brake cable-connecting apparatus as defined in the seventh aspect of the invention, the plate springs are integrally formed with a connecting portion and mounted on the operating lever at the connecting portion.
Pursuant to the eighth aspect of the invention, the plate springs can easily be disposed in the brake cable-connecting apparatus when such a pair of plate spring is used as a plate spring as practiced in the seventh aspect of the invention.